This invention relates to hand held non-contact voltage testers, and particularly to such a device with a combination of features which facilitates the use of the device.
Hand held non-contact voltage testers of the type to which the present invention relates are well known. For example, they are shown in U.S. Pat. Nos. 3,822,598; 3,919,631 and 5,103,165. Such devices are typically pen-like pocket held and battery operated, and have a number of uses.
Such devices are used to detect whether a voltage is present at the location or wire being probed. If there is a voltage present, the device either lights and/or an alarm sounds off, repeatedly or continuously for as long as the probe tip is held in the vicinity of the voltage, to signal the operator that a voltage is present. Knowing a voltage is present, the operator will exercise caution around the location or handling the wire, or will turn the voltage off, for example at a circuit breaker panel.
If a location or wire is probed and the device does not light up or sound off, the operator may assume there is no voltage present and may exercise less caution than if a voltage was indicated. In fact, there may be a voltage present, and the reason for the device not indicating the voltage is that the batteries are dead, or the light or sound indicating device are non-operational.
Therefore, there is a need for a non-contact voltage tester which gives the operator an indication of whether it is operable.